1. Field of the Invention
This invention relates to a control for an ink ribbon feed device for office machines, particularly typewriters, with a ribbon spool, a transport wheel and a connecting element to transmit the transport drive from the universal bar to a ribbon feed device.
2. Description of the Prior Art
Ribbon feed devices are known which are provided with a transport lever having a transport pawl, the lever being situated in the center of the spool or at a distance therefrom and the pawl being held by a torsion or traction spring in the teeth of the transport wheel, and with a connecting element to the universal bar, with a restoring spring.
A drawback of this system is that a connecting element from the universal bar is attached to the actual transport wheel, so that this latter can easily jam or tilt over. For this reason, use is made of complicated bearing points, expensive to produce, with bushings and a long rivet, or else of U-shaped and double-U-shaped supporting devices manufactured at great expense. The force taken off by the transport lever is only variable if the disadvantages of the transmission characteristics of this system are accepted. This is the reason why the transport levers are comparatively long and extend from the assembly, precluding a compact construction. It is thus hardly possible for ribbon feed devices of this kind to be adapted to adjacent units of machinery as and when these are developed further. The force and speed characteristics for the longitudinal movement of the ribbon remain constant, having an unfavourable effect on the operator's "touch", as the transport lever is directly articulated to the universal bar via a connecting element.